Detection rules › Sigma

Suspicious Loading of Dbgcore/Dbghelp DLLs from Uncommon Location

Status
experimental
Severity
high
Log source
category image_load, product windows
Author
Swachchhanda Shrawan Poudel (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects loading of dbgcore.dll or dbghelp.dll from uncommon locations such as user directories. These DLLs contain the MiniDumpWriteDump function, which can be abused for credential dumping purposes or in some cases for evading EDR/AV detection by suspending processes.

MITRE ATT&CK coverage

TacticTechniques
Defense Impairment
Credential Access

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 7: Image loaded

Rule body

title: Suspicious Loading of Dbgcore/Dbghelp DLLs from Uncommon Location
id: 416bc4a2-7217-4519-8dc7-c3271817f1d5
related:
    - id: 9f5c1d59-33be-4e60-bcab-85d2f566effd
      type: similar
status: experimental
description: |
    Detects loading of dbgcore.dll or dbghelp.dll from uncommon locations such as user directories.
    These DLLs contain the MiniDumpWriteDump function, which can be abused for credential dumping purposes or in some cases for evading EDR/AV detection by suspending processes.
references:
    - https://blog.axelarator.net/hunting-for-edr-freeze/
    - https://www.zerosalarium.com/2025/09/EDR-Freeze-Puts-EDRs-Antivirus-Into-Coma.html
    - https://www.splunk.com/en_us/blog/security/you-bet-your-lsass-hunting-lsass-access.html
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-11-27
modified: 2026-01-09
tags:
    - attack.credential-access
    - attack.defense-impairment
    - attack.t1003
    - attack.t1685
logsource:
    category: image_load
    product: windows
detection:
    selection_img:
        Image|contains:
            - ':\Perflogs\'
            - ':\Temp\'
            - ':\Users\Public\'
            - '\$Recycle.Bin\'
            - '\Contacts\'
            # - '\Desktop\'
            - '\Documents\'
            # - '\Downloads\'
            - '\Favorites\'
            - '\Favourites\'
            - '\inetpub\wwwroot\'
            - '\Music\'
            - '\Pictures\'
            - '\Start Menu\Programs\Startup\'
            - '\Users\Default\'
            - '\Videos\'
            #  - '\AppData\Local\Temp\' some installers may load from here
    selection_dll:
        ImageLoaded|endswith:
            - '\dbgcore.dll'
            - '\dbghelp.dll'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high
regression_tests_path: regression_data/rules/windows/image_load/image_load_win_susp_dbgcore_dbghelp_load/info.yml

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

selection_img:
    Image|contains:
        - ':\Perflogs\'
        - ':\Temp\'
        - ':\Users\Public\'
        - '\$Recycle.Bin\'
        - '\Contacts\'
        - '\Documents\'
        - '\Favorites\'
        - '\Favourites\'
        - '\inetpub\wwwroot\'
        - '\Music\'
        - '\Pictures\'
        - '\Start Menu\Programs\Startup\'
        - '\Users\Default\'
        - '\Videos\'

Stage 2: selection_dll

selection_dll:
    ImageLoaded|endswith:
        - '\dbgcore.dll'
        - '\dbghelp.dll'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Imagematch
  • :\Perflogs\ corpus 9 (sigma 9)
  • :\Temp\ corpus 11 (sigma 11)
  • :\Users\Public\ corpus 13 (sigma 13)
  • \$Recycle.Bin\
  • \Contacts\ corpus 4 (sigma 4)
  • \Documents\
  • \Favorites\ corpus 5 (sigma 5)
  • \Favourites\ corpus 4 (sigma 4)
  • \Music\ corpus 3 (sigma 3)
  • \Pictures\ corpus 4 (sigma 4)
  • \Start Menu\Programs\Startup\
  • \Users\Default\ corpus 3 (sigma 3)
  • \Videos\ corpus 3 (sigma 3)
  • \inetpub\wwwroot\
field:"Image" kind:match
ImageLoadedends_with
  • \dbgcore.dll corpus 6 (sigma 6)
  • \dbghelp.dll corpus 6 (sigma 6)
field:"ImageLoaded" kind:ends_with